Field
The presently disclosed subject matter relates to methods and systems for monitoring distillation tray performance. More particularly, the presently disclosed subject matter relates to detecting operational conditions in trays of a distillation column using an optical fiber for distributed temperature and/or acoustic measurements.
Description of Related Art
Components of certain equipment, such as that used in the petroleum and petrochemical industry, which includes the exploration, production, refining, manufacture, supply, transport, formulation or blending of petroleum, petrochemicals, or the direct compounds thereof, are often monitored to maintain reliable and optimal operation. However, such components can involve harsh conditions, such as high temperature, high pressure, and/or a corrosive environment, making it difficult or costly to obtain reliable measurements.
Monitoring of operational conditions of distillation column trays can provide for enhanced control an operation. For example, remedial action can be taken if an unstable operating condition, such as flooding and/or dry-out conditions, is detected. Moreover, tray performance can be optimized by, for example, maximizing the throughput while maintaining stable operation.
Conventional approaches to monitoring of operational conditions of distillation column trays can include measuring delta pressure across a column. As the column approaches an unstable condition, such as flooding, more liquid is held up by the upward vapor flow, and the delta pressure will increase. When the delta pressure reaches to a pre-selected threshold, operators can cut back the throughput to avoid a runaway, a condition when the delta pressure increases exponentially and the column reaches to an unsafe operating condition. However, it is well known that the delta pressure may fluctuate or change for many reasons other than flooding. Thus, thresholds indicative of flooding may not be reliable as a flood indicator. For example, the delta pressure can vary depending on the grade of the feed. Lighter grades can tend to flood sooner than the heavier ones. In addition, the delta pressure is not sensitive to subtle and localized flooding when the flood occurs in one single tray. Since a threshold is conventionally used, the delta pressure provides merely a rigid “yes” or “no” to the operators for flooding warning.
Other conventional approaches to monitoring of operational conditions of distillation column trays can include “gamma ray scanning.” Generally, these techniques measure the density of the material through the vessel wall to determine the level of the froth on each tray as an indication of flooding. However, such techniques cannot be used for real-time operation and control.
Accordingly, there is a continued need for improved techniques monitoring the operating condition of individual trays within a distillation column.